Lymphatic and Immune System Flashcards
4 Functions of the Lymphatic system
- Maintenance of blood volume in cardiovascular system
- Filtration of foreign material to defend against infection
- Development/maturation of lymphocytes
- Initiation of specific immune responses
4 basic components of Lymphatic system
- lymph (fluid)
- Lymphatic vessels
- Lymphatic cells
- Lymphatic organs
What do Lymphatic vessels do?
-transport interstitial fluid (Lymph) from the tissues back into the blood
- Due to nature of blood and the blood system, we lose approx 3-4 L fluid per day (if not returned we’ll die)
- liquid leaks into tissue between capillaries (needs to as that’s how O2 and nutrients get to cells) - lymphatic system is involved in returning this fluid - and lymphatic vessels important
Components of lymph (5)
-colour if healthy
Comprised of;
- interstitial fluid
- solutes (i.e. salt, sugar -> anything not dissolved by cells)
- lipids
- foreign material
- immune cells
*Is clear if healthy
Lymphatic capillaries - what they do & where they are
-how they’re structured
- Allow interstitial fluid to drain back into circulation
- surround capillary beds (capillaries allow fluids, nutrients, proteins and even cells to pass into tissues)
- are soft, have openings so that fluid can flow through passively (is NO pump)
- structured so that liquid will flow into capillaries in one direction
- have little valves
- structured so that liquid will flow into capillaries in one direction
How does Lymph move?
-negative implications
- muscles, movement, gravity etc stimulates the valves to open and close, thus moving the lymph.
- if in coma & can’t move, start getting lymphatic & blood volume problems because of this
Lymph Nodes - what they do, what they are
- Is where lymphatic vessels drain into
- are filtration systems -> are packed full of lymphocytes
*critical as body needs to ensure it isn’t allowing anything that shouldnt be in the body back into the blood stream
Lymph Nodes -> structure
-size
- Has blood flow coming in and out (artery and vein) as well as afferent lymphatic vessels and a single lymph vessel (that leaves)
- more than one entry but only one exit
- lymph vessel that exits is going to thoracic duct
- usually greater than 1 cm in size
Extra role of lymphatic vessels in lower GI tract
-chyle
- Allows for transport of lipids
- Lipids are large and insoluble
- are a classic source of energy, but hard to get into bloodstream -> lymphatic system helps get them in
- Lymph containing lipids = chyle (is yellow)
What lymphatic vessels collect into (2)
- lymphatic vessels collect into lymphatic trunks
- trunks eventually merge to form 2 ducts;
1. Right lymphatic duct
2. Thoracic duct (drains 3/4 of lymph in body
What lymphatic ducts do
- joins lymphatic and cardiovascular systems together
- Ducts run right alongside blood, allows lymph to fall back into blood withOUT pressure
When things go wrong in lymphatic system
- Blockage or disruption of lymphatic vessels or flow leads to fluid build up = lymphoedema
- Damage to thoracic duct or trunks can lead to build up of chyle in lungs = chylothorax
Antigens - what is it
-what triggers immune reaction
- Antigens = antibody generating substances (activates immune system)
- foreign substances (aka antigens) that enter the body trigger an immune reaction
Role of lymph nodes and antigens
- 2 ways antigens get to lymph node
- dendritic cells (what do they do)
-Lymph nodes trap antigens coming from tissues
- dendritic cells (are in every tissue in the body) are special immune cells in the tissue that also CAPTURE antigens to take to lymph nodes
- long process capture antigens, internalise it and transport it to lymph node
Lymphocytes
- are immune cells that live in lymph nodes
- are the key to adaptive immunity
- enter lymph nodes from the blood
- antigens enter from the tissue
-Lymph nodes therefore bring antigens and lymphocytes together (to accelerate immune response)
Lymph organs
-2 types
-Contain large number of lymphocytes in a framework of non-lymphoid cells
2 types;
1. Primary lymphoid organs: bone marrow and thymus (is where lymphocytes develop -> bone marrow = B cells; thymus = T cells)
2. Secondary Lymphoid organs: lymph nodes and spleen (lymphocyte responses)
2 main types of lymphocytes in body
-where found in lymph nodes
- T Cells: cell mediated immunity: help other cells
- B cells: antibody mediated immunity: make antibodies
*within lymph node, T cells are on the inside and B cells are on the outside
Spleen
- filters antigens from blood
- if something invades bloodstream, there are no lymph nodes there to filter
- spleen is like a giant lymph node that filters blood (same structure as lymph node but no vessels
*if spleen ruptures/lost become more prone to blood infections
Cardiovascular system vs Lymphatic system
- Fluids transported
- major vessel types
- mode of transport
- sites of filtration
- major point of intersection (vessels)
Cardio - Lymph
Blood; Lymph
Capillaries, veins, arteries; lymph vessels & lymph trunks
Pressure from heart; passive - gravity and muscle movement
spleen; lymph node
Thoracic duct; vein in chest
Immune system of all vertebrates made up of (2 systems)
- Innate Immune system (inborn defense mechanism) - found in all classes of animals
- Adaptive immune system (Acquired immune defenses) - are unique to vertebrates and generated during lifetime of an individual
3 components of immune system
- Specialised immune cells (that do things)
- Specialized receptors and defense molecules
- Specialised immune organs/tissues
Level of protection and lines of defense
- First line = barriers and defense molecules (offers lowest level)
- Second line = phagocytosis and inflammation
- 3rd line = activation of T cells and B cell responses (this is adaptive immunity that offers highest level of protection and memory)
*innate immunity works first, then adaptive
Innate vs Adaptive
Innate:
-Include phagocytes and granulocytes
-many types of recognition receptors on each cell
-inherit genes from mother and father
-present from birth
-mainly recognise microbial molecules (non-self)
Adaptive:
-comprise of lymphocytes
-one type or recognition receptor on each cell
-receptors assemble from multiple gene fragments
-formed after birth
-Recognise ALL antigens (self and non-self)
What happens to lymphocytes once made
Naive T & B cells
- Released and circulate in bloodstream
- For majority of cells - nothing happens
Naive T & B cells = lymphocytes that never seen an antigen
B Cells - what they do
-antibody binging
- B Cell receptor promiscuous ->sticks to things directly
- once it sticks, it activates then divides, pumping out same cells
- It will start secreting its B-cell antigen receptor (BCR) as an antibody once it is activated by an antigen
- B cells are the antigen making factories
- antibody binding: just bind and tag antigens. If binds to a toxin, it sticks to it and neutralises it
T Cells - what they do
- Not as promiscuous as B cells -> need another cell to show it where antigen is
- T cell antigen receptor (TCR) is related to immunoglobulin but evolved separately
- TCR can only recognise an antigen when it is presented as a peptide in a special molecule found on antigen-presenting cells
- antigen presenting cells = dendrite
*only right T cell will respond once dendritic cell shows it a peptide
2 main types of T cells
- Helpers
- Killers
- either help or ill infected cells in tissue
- overall they provide cell-mediated immunity
Interaction between T cells and Dendritic cells
- Dendritic cells constantly moving around through body
- once it has acquired an antigen, it takes it to the lymph node and shows T cell
- T cells are constantly sending out signals to dendritic cells as to where lymph node is -> dendritic cells only recognise signal once it has an antigen
T cell response to receiving a peptide of an antigen
- When the right T cell fits with the antigen, it proliferates (which is the response)
- swollen lymph node can sometimes occur as lymphocyte division cause the lymph node to swell.
-Unlike B cells, T cells can’t secrete receptor - they therefore go to the tissue to help fight and kill infected cells
Adaptive immune response - memory
- Specificity, diversity and memory are all properties of adaptive immune response
- first time immune system exposed to antigen, primary response takes a while to build up
- after infection, most of T cells and B cells die off, but slightly more than what began with is left
- these are the memory B & T cells
- second infection with same antigen = much faster and quicker immune response because there are more cells that have right receptors to that antigen
